Mtjltioffice telephone system



April 10, 1928. 1,665,273

.l M. L. NELSON MULTIOFFIGE TELEPHONE SYSTEM Original Filed Jan. 18. 1924 6 Sheets-Sheet l April 10, 1928.

M. L. NELSON MULTIOFFICE TELEPHONE SYSTEM origina Filed Jan.1s. 1924 e sheds-sheet E s N 'w is s Q k' (r) l J m e WN: o o o o n nl* April-1o, 192s;

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April 10, 1928.

April 1o, 192s.

l M. L. NELSON MULTIOFFICE TELEPHONE SYSTEM Patented Apr. 1o, laas.

UNITED STATES PATENTA OFFICE.

MARTIN L. NELSON, 0F PARK RIDGE, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, l TO AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINGIS, A CORPORATION OF DELA- WARE.

MULTIOFFICE TELEPHONE SYSTEM.

Application filed January 18, 1924,'Sera1 No. 686,946. Renewed August 29, 1927.

and intended for a subscriber whose line` terminates in an automatic oilicc.

This case may be considered an improvement on my priorcase, Serial No. 443,688, tiled February 9, 1921, and when considered in the light otthis prior case, t-he principal feature 'of the present invention relates to the provision of new and improved circuit arrangements whereby the B operators senders are common 4to a plurality of l operators instead of being individual to one operator.

A. further `feature of the present inven tion relates to the provision of new and improved circuit arrangements whereby only one set of controlling push buttons is required at afB opcrators position for the purpose of setting up the desired numbers, arrangements being provided for associating the common push buttons with a new sender while the sender last used is still sending out the number indicated by the associated register.

It is specifically an object of the invention to provide a step by step switch individual to the above mentioned set of push buttons which disassociates the push buttons from the register sender last used and automatically associates the push buttons with a newsender independent of any special act on the part of the operator. y

A further object ot' the present invention is to simplify the circuits through which the push buttons vcontrol a selected register sender so as to permit a relatively small number of wipers to be used on the switches which complete the connections :from thc push buttons to the register sendersfs.

There are several other objects of the present invention which may be classiiied broadly as having to do with the production of circuit ar angeinents whereby the apparatus is simplified to thegreatest possible extent consistent with good operation, and whereby the operations to be performed by an operator in setting up a call are reducedto the smallest practical number. These objects,

together with the foregoing, will be ex.- plained 4fully hereinafter.

Jreferring now to the accompanying drawings comprising Figs. l-6, inclusive, they show by means of the usual circuit diagrams a sufficient amount of apparatus in a system embodying the principles of the invention to enable all the new features of the case to be understood. In order for the drawings to be understoodbest, Fig. 2 should be placed beneath Fig. l, with Fig. 3 to the right of Fig. 2, and with Fig. d to the right of Fig. Figs. 5 and G show a desirable modification of the circuit arrangements at the B operators position and, when used, should be substituted for Figs. l and 2, respectively.

Fig. l shows a trunk line extending trom the jack J at an A operators position in a manual oiiicc by way of the trunk circuit TC at a cB operators position to the selector D in an automatic oliice. The remaining equipment shown in this drawing and in Figs. .9J-et, inclusive, is located at the oilice in which the B operators position is located. This position may be located either in the calling manual oiiice or in the automatic ottico, depending upon which is more economical in any given case.

The selector D, Fig. l, is mechanically of the well known vertical and rotary type of switch having its bank contacts arranged in horizontal rows or levels, and its circuits are arranged for the well known two-wire method of operation.

The finder F, Fig. l, is mechanically of the well known rotary type of switch whose wipers are advanced in aorwa-rd direction only and have nonorinal position. This finder has access to a group of trunks of which the trunk circuit TC is one.

The register-sender selector, Fig. 2 is mechanically the same type ot switcll as the iinder F and has access to a plurality ol register senders. one oi. which shown in Figs. 3 and Ll. 'llhelinder F and the register-sender selector RSS, together with the associated relays, are termed a iindenselector link and will be referred to hereinafter as a link circuit. It has been assumed that there are three of these link circuits at the B position shown, although this number may be increased to any desired number in case it is found that three of them are not enough.

The link selector LS, Fig. 2, is mechanicalmay be connected to the link circuit through the medium o conductors 91-95, inclusive,

as is .indicated in the drawing. In `this case, the finder F has Vaccess to part et the trunks and Lthe twin finder has access to the remaining part oit the trunks, separate start wires being used for each group.

The register set shown in Fig. -3 comprises .the tour digit registers DR-l---DR-fl,i-n elusive. Each of these Vregisters is arranged to ground a certain one of the ten impulse stop conductors 251-260, inclusive, luider the control 'of the operatorie numerical push buttons. The relays 205, 2175, 225,'and 235, it may ybe 4pointed out, when taken together, constitute a iregistercontrol sequence switch, and the two step relays 206,216, 226, and 236, taken together compriseV a sender controlling sequenceV switch. Regarding these two step relays, relay 206 for example, it ymaybe pointed out that the lower winding eonsistsot -a small number of turns of :high

Vresistance wire, while the upper winding eonsistsof al large number of turns ot Irelatively low resistance wire. The adjustment vof this relay is suc-h that when current 'flows through the lower winding alone the locking eontact marked l closes, while the remaining conta-cts of the relay .remain as :they are. These remaining contacts are marked .27 to indicate that they operate upon the second lstep of the relay which occurs when it is energized through its twowindings in series.

rlhe sender, Fig. ll, is mechanically ot the well known rotary type of switch whose wipers move in a forward direction only and are. advanced upon the deenergization rather than upon the energization oft the stepping magnet.

A more or less general description of the apparatus .having been given, lthe detailed description of the operation will Vnew be taken up. For this purpose it will be assumed that the A operator receives a call for a subscriber whose line terminates in the automatic office to which calls `are handled through the B position shown in Fig. l.. Accordingly, 'the A operator communicates with the B7 operator through the medium of the well known order wire (not shown) and informs the B operator of the desired number, together withthe identity of the calling office. The B operator aeeordingly assignsa trunk to the A operator inthe group lbelonging to the calling votiee, the trunk comprising conductors A2 and 3, for example` associated with the ack J at the calling A position. The B operator also depresses her non-locking assign button 22, thereby placing ground on the start wire 3l at the lower contactsl et the said push button. Also, the normal ground potential is removed irom testv conductor 3() at the upper main spring et the push button and the conductor 30 is connected with `relay 2l. 'llhefoperator is instructed to hold the push button 22 depressed until the indicating lamp lOl, associated with her vkey set, Fig. 2, becomes lighted in u mauner which will now be explained.

Responsive tothe ground potential heine.` placed upon start; conductor lll, relay Sin' energizes through its lett hand wim-ling und. places ground on conductor 83 at armature 99 so to lprerent the eiiergizz'iliou o't relay 131 of the link circuit shown iuFig. il while the start wire still grounded. ,ls a l'urther result o'l Athe placing ol'- the ground potential on start conductor 3l, a circuit is clef-1rd for relay G6 through the normallyclosed con `tacts controlled `by armature 73, which circuit ineludes also conductor Sl, arn'mt'ure lol and its working contact', and resii'stance l29. Start relay titi, upon ei'iergizing, places ground on conductor 85 at arn'iature 7G, thereby starting the operation et' the register sender selector RSS ot the pre-selected link circuit ttl in a manner to he pointed out more liully hereinafter. Relay titi also closes at armature 178 a lcircuit Yfor switching relay (35 and stepping magnet 6i' in series, and at arn'iatu-re 77 connects test wiper (38 to the `iunction of relay G5 and stepping` i'nagnet T7. Assuming lirst that 'the wipers (iS-70, inclusive, of the linder F are standing upon the contacts in which conductors 28- 30, inclusive, lof the trunk circuit TC terminato, the operation ol armature 77 does not perform any particular function owing to the tact that conductor 30 is ungrounded, and switching relay (35 energizes innuediately, seizing the trunk circuit TG. Assuming, however, that the wipers (30u70, inclusive, are standing upon some other set ot contacts as indicated in the drawings, test: wiper 68 is in engageifnent with u grounded contact and switching relay (35 is short circuited and does not energize. lln this case, stepping magnet ('37 is energized through test `wiper (S8, und the wipers ot the linder are advanced step by step in search of the trunk circuit TC owing lo the liuzzerdilnf action ot stepping magnet 67, which interrupts its own circuit.

Then the contacts in which the conduttore 28-30, inclusive, terniinate are reached, test wipe-r (58 engages an ungrounded testi contact and switeliing relay 65, being no longer .short cireuited, 'energizes in series with stepping magnet 16T. Stepping magnet (57, howerer. doesnot venergize at this time `on account ot' the high resistance et switching relay (to,

t lf 1,061.1,

Upon energizing, switching relay 05 closes a, br'idge across wipers 69 `and 70 at armatures 74 and 75, which bridge includes conductors 79 and 80 and the normally closed contacts controlled by armature 149, Fig. 2; closes a point in the circuit oit the indicating lamp 101, Fig. 2, at armature 71; closes a local circuit for start relay and disconnects it trom the start wire at armature 78; and aty armature 72 opens the test circuit and places ground on test wiper 0S, thereby closing a circuit over conductor 30 and the upper contacts of the assign button tor relay 21. Relay 21 accordingly energizes; disconnects ground from the central contact ot the assign button at armature 25; and closes a circuit for the busy lamp 8 and the lower winding ot the electro-polarized relay 0 in multiple at armature 26, whereupon the lamp 8 becomes lighted to give a subsequent indication to the operator to aid her in assigning non-busytrunks. Relay 9, however, does not operate at this time owing to the fact that its lower winding, consisting ci a relatively small number oit turns of wire having a comparatively high resistance, is not able to energize the relay sufficiently to attract its armature. As a further result of the energization ot relay 21 it connects the closed bridge including conductors 28 and 20 across the conductors leading to the selector l) and disconnects the latter `from the trunk circuit TC. lhen this occurs, line relay 35 in the selector'D energizes over the above traced closed bridge and closes at armature 40 a circuit :tor relay 30, whereupon relay 36 energizes and at armature 41 prepares certain operating circuits within the selector', and at armature 42 opens a point in the circuit ot release magnet 53 and prepares a circuit t'or vertical magnet 55.

Returning now to the operation of the link circuit, it will be remembered that, upon the energization of start relay 66, a. circuit was closed Ylor start relay 132 ot the register sender selector RSS. This circuit includes conductor and armature 107 and itsresting Contact. Y Upon energizing over this circuit, start relay 132 closes at armature 156 a cir cuit for relay 181 as :follows: from ground by way ot the working contact ot armature 154 and said arniatln'e, working contact and arulaturc 150, relay 131, resistance 134, arma# lure 15?) and its working contact, and resistance 120 to battery. Relay 131, however, does not energize over this circuit, owing` tothe tact that it is short circuited by the ground potential applied over conductor 53 and through armature 155 and its resting contact to the `junction et its winding and resistance 134 by armature 99 ot relay 9S. As a further result of the energization ot start relay 132, it closes at armature 157 a circuit for relay 133 and stepping magnet 135 in series, and at armature 15S 'connects test wiper 145 to the junction et the winding ot relay 133 and the winding et stepping magnet 135. Accordingly, the register-send er selector' RSS selects an idle register sender in substantially' the` same manner as the trunk circuit TC was selected by the finden l, and when an idle reg'ster sender is reached by the wipers 141-140, inclusive, under the `control et stepping magnet 1.35, switching relay 133 is no longer short circuited and 4energizes in series witlrstepping magnet 135, which magnet does not energize at this time on account o1 the relatively high resistance ot switching relay Upon energizing, switching relay 133 disconnects test wiper 145 trom the junction ot relay 133 and stepping magnet 135 and connects it to ground instead, thereby making the seized register sender busy to the other selectors `having access to it; connects up the wipers 141-144, inclusive, and 140 at armatures 161-1G4, inclusive, and 166, respectively; and at armature 150 completes a circuit for the lamp 101 as follows: troni `ground by way ot the working contacts and armature 71, conductor 84, working contact and armature 159, contact in the banlc, ot wiper 125 and said wiper, and the lamp 101 to battery. Responsive to the closure ot this circuit, the lamp 101 becomes lighted, A

informing the operator that she may now release the assign push button and set up the desired number on her number push buttons. When the assign button is released, ground is removed from start wire 3 1, permitting relay 98 to deenergize, whereu] )on ground is removed trom conductor E13, per mitting relay 131 to energize over its above traced circuit, which includes armature 150 and its working contact and resistance 1211-. Relay 131, upon energizing, disconnects conductor 83 from the unction ot its own wilnlf ing and resistance 184 and connects it to conductor lor a purpose to be explained hereinafter.

The operator may new proceed to set up the number which we will assume is the number 5078. Accoriilingly, the operator iirst depresses the fifth push button, thereby grounding wipers 122 and 124, causing a ground potential to be extended through the working contacts and armatures 102 and 104, wipers 1.42 and lil/l, comite-tors 172 and 174, and the second and Lloul'th arlnaures o1 relay 205 and their respi-ictive resting cdutacts to relays 202 and 201. A.ccoi `lin'ly, relays 202 and 204 become energized and eachcloses a locking circuit :tor itself at its lett hand armature through relay and the grounded test conductor 175. 'llhe loch ing circuit for these relays does not become etrective immediately, however, owing to the ground extended to each over the above traced circuits. However, when the operator releases the lilith push hutten, the initial lll I reeds/re circuits of relays 20,2 and 204 are opened, whereupon the locking circuit for these relaysbecoines effective and relay 205 energizes; prepares a circuit for the siinilar relay 215 of the digit register Dlt- 2 at its upper armature, and at its four lower armathe Worliing contacts and armatures 163 and 164, Wipers 143 and 144, conductors 173 and 174, third and fourth armatures and their Working contacts of thc transfer relay 205` and the third and fourth armatures and their resting contacts of relay 215,l for rclays 213 and 214 of the second digit register Dlt-2. Accordingly, relays 213 and 214 energize and each closes at its left handV armature a locking circuit for itself through transfer relay 215 and the upper armature and its Working Contact of the transfer relay 205. This locking circuit, however, does not become effective until the operator re- Y.leases the push button, at .which vtinie the short circuit is removed from around relay 215, permitting 1t to energize and transfer the conductors; 171-174, inclusive, to the relays r221224, inclusive, respectively, of the third digit register Dfi-3.

llifhen the operator depresses the seventh push button, ground is placed on Wiper 121, thereby closing a circuit through the resting contact and armature 150, Working contact and armature 161, Wiper 141, conductor 171, first armature and Working contact of relay 205, first armature and its Working Contact of relay 215, and the first armature and its resting contact of relay 225 for relay 221. Relay 221 accordingly energizes and coinpletes a locking circuit for itself at its left hand armature, which becomes effective upon the release of the seventh push button to maintain the relay locked up and to energize the transfer relay 225, which transfers the conductors l71--174, inclusive, to `the relays 231f234, inclusive, of the fourth digit register JDR-4.

'Vhen the operator depresses the eighth push button for the fourth and last digit in the desired nulnher, ground is placed on the second 'Wiper 122 of the link selector, closing a circuit as previously traced to conductor v172 and thence hy Way of the second armatures and working contacts of relays 205, 215, and 225 for the second relay Y232 of the fourth digit register 13R-4. Relay 232 accordingly energizes and at its left hand armature ,closes a. locking circuit for itself which, upon the release of the eighth push button hy the operator, is effective in holding the relay locked up and in energizing relay 235. lie ay 235, upon energizing, dis'- connects atits tivo lower arnnitures conductors 171 and 172 frein relays 231 and 232 and connects thein to the inipulse conductors 2li and 242. As a` fur her result of the energization of relay 235, it places ground on conductor 270 at its upper armature, thereby grounding start conductor 243 through the lower armature and its resting contact of relay 234i, resulting in the sender heing star cd in a inannrr to he pointed out here inafter. As a further result of the ground potential being placed on conductor 270, a circuit is closed through the upper arn'urture and its resting` contact of relay 230, conductor 176, Wiper 146 of the registersender selector RSS, armature 166 and its working Contact, and relay 123. Relay 1&3 accord` ingly encrgizes; disconnects wipers 141 and 'i4-2 from the key set at armatures 149 and 150 and connects thein with the conductors 79 and 30, at the saine time opening the local bridge across conductors 79 and 80 at the normally closed contacts controlled hy arinature 149` leaving the line relay of the iii-st selector D energized tlufough coiiductors 171 and 172 which are non' connected through the lower armature and Working contacts of the transfer relays 205, 215, 225, and 235 to the closed bridge in the sender including conductors 2441 and 242. As a further result of the energizatien of relay 128, it closes at armature 143 a locking circuit for relay ($0 including conductor 31 and armature 73 and its Working contact` and at armature 147 disconnects the test conductor from relay 130 and connects it to ground. Relay 130 accordingly deenergizcs and opens the circuit of relay 131 at armatures 153 and 154r.hcreupon relay 131 deenergizes. Relay 130 also opens a point in the initial circuit of start relay 6G of the finder F, leaving the said start relay energized over the locking conductor S1.

Responsive to ground being placed on the testconductor of the link at armature 147 of relay 12S, as ahove pointed out. a circuit is closed through test wiper 120 and interruptor contacts 105 for stepping magnet 102 ol'iiho link selector, whereupfni the said stepping magnet en'ergizes and interruptsI its on'ndcircuit, resulting in the Wipers 121420, inclu-- sive, being advanced into engagenunt with the contacts of the Iirst idle sender.

Returning now to the sender, Fig. 4, responsive to the ground heing placed upon start conductor 243 upon the operation of the transfer relay 235 of the unitsI register, above pointed out, a circuit is closed through thc interruptor 304, (upon the lirst succeeding operation of the interrupter), resting contact and armature 310. and stepping 1nagnel; 303 to hattcry, Stepping n iagnet 303 accordingly energizes` and moves the associated pawl into engagement with the next notch in the` wiper driving ratchet wheel. Magnet 303 also opens at contacts 301 a point in the bridge across conductors 241 and 242, but nothing happens responsive to this owing to the fact that contacts 301 are shunted by armature 312 and its resting contact. Upon the subsequent deenergizat'ion of stepping magnet 303, due to the operation of the interrupter 304, the wipers 307 and 308 are advanced one step, whereupon wiper' 307 engages a grounded bank contact, closing a circuit for pick-up relay 306. Relay 306 accordingly energizesmand places `ground `on conductor 2441 at armature 313 through armature 311 and its resting contact.

upon the conductor 244, the lower winding of the two step relay 206, Fig. 3, is energized through the upper armature and resting` contact ot the said relay 206, whereupon the armature proper of the relay takes the first step. closing the locking contacts indicated by the number 1 on the drawings. This winding, however, does not energize the relay sufiiciently to causethe remaining contacts to be operated at this time;-Y

As a further result of the above mentioned operation of pick-up relay 306 or the sender, it removes the shuntirom around the interrupter contacts 301 at armature 312. Accordingly, upon each of the following energizations of stepping magnet 303, the bridge across conductors 241 and 2112 is opened at contacts 301, resulting in the deenergization of the line relay 35 of the selector D, Fig. 1. The operations of the stepping magnet 303 continue under the control of interrupter 304 until tive interruptions have been-M produced in the outgoing control circuit at contacts 301 or, in other words, until the digit 5`- has been sent oui. Following the iiith interruption in the outcoing control circult,slep1iing magnet 303 ueenergizes and advances wiper 303l into engagement with the fifth impulse stop conductor 255, whereupon stop relay 305 is energized over the following circuit: `ironi ground by way .ot the lower ariiiatur'e ot relay 206, Fig. 3, and its resting contact, right hand armature andresting contact ot' relay 201, right hand. armature and working contact of relay 202, middle right hand armature and resting contact ot relay/203, middle armature and working contact oi relay 2041, the lijlth impulse stop conductor 255, `the associated contact in the bank ot wiper 303 and the said wiper, and stop relay 3075 to battery. Upon energizing, stop relay 305 removes ground*fromfconductor 24A and closes a locking circuit at armature 311,

which locking circuit includes armature 313,

and its working contact. Responsive to the removalV of the ground potential trom conn Respon-` sive to the ground potential being placed ductor 244, i the shunt is removed from around the upper winding of the two step relay 206, whereupon the said relay energizes fully and operates its remaining armatures. At its lower arn'iature, relay 206 disconnects groui'id from the contacts ot the relays 201-204, inclusive, and extends ground through the lower armature of relay 216 and its resting contact to the armatures ot' the relays 211-214, inclusive. At its upper armature, relay 206 disconnects conductor 2411 from the junction of its own. windings and extends the said conductor 244 by way of the upper armature of relay 216 audits resting contact to the junction ot the windings of the said relay 216.

The thousands digit 5 lin the number has ,been transmitted and the sender isnow in an oii' normal position. Accordingly, it will be necessary `to restore the sender to normal before the next digit can be sent out and, for this reason, stop relay 305, upon energizing as abovepointed out, in addition to removing ground trom the conductor 244 and closing a locking circuit for itself at armature 311, disconnects stepping magnet 303 from the interrupter 304 and connects it to wiper 307 through its interrupter contacts 302. Relay 305 also places a shunt around the sending contacts 301 at armature 309, so as to prevent the outgoing control circuit from being interrupted during the return to normal of the sender. Stepping magnet 303 of the sendernow operates in a buzzerlike manner to advance the wipers 307 and 308 to normal. This operation is arrested when wiper 307 passes off the last grounded bank contact. As a further result ot wiper 307 passing oit the last grounded bank contact, the circuit ot' pick-up relay 306 is opened. Pick-up relay 306, however, slow acting and does not deenergize immediately.

In the selector l), Fig. 1, each time line relay 35 (fleenergizes in response to one ot the live interruptnins produced Vin 'i circuit by the sender as above.described, it closes at armature 10 a circuit tor vertical magnet 55 as Yfollows from ground by 'way ot the resting Contact and armature 43, armature L10 and its resting contact, armature42 and its working contact, series relay 37, and vertical magnet 55 to battery. By the operation 'et vertical magnet 55, the wipers S0-52, inclusive, of theswitch are raised step by step and come to rest opposite the iit'th level of bank contacts.` Relay 37 energized in series with vertical magnet 55 and, being slow acting, maintains its armature attracted throughout the vertical movement. Relay 37, in combination with cti' normal contacts 56, which close upon the iirst vertical step, closes at armature 13 a circuit through interrupter contacts 57 for stepping relay 33. Stepping relay 36 thereupon energizes and closes a locking circuit for itself at armature 44, and at' armature prepares acircuit forrotary magnet 48.

At the end of the vertical movement, slow .acting seriesV relay 37 deenergizes and-- com f pletes the c1rcu1t of-rotary magnet 58, whereand, near the end of its stroke, opens the circuit Vof. stepping relay 38 at interruptor contacts?. Stepping relay 38accordingly deenergizes and opens' the circuit oi rotary magnetV 58v at armature 45., whereupon rotary magnet 58 deenergizes also and aga-in closes its interrupter contacts 57:

Assumingthatthe trunk terminating in the first set of bank contacts is idle, no ground potential is encountered-by test wiper 51 and switching relay 39 energizes immedi ately, seizing the trunk. In this case, however, it will be assumed that the trunk ter-- minating in the irst set of bank contacts is busy, in which case test wiper 51 engages a grounded bank contact. Vand switching relay 39 is short cireuited and does not energize. Steppingrelay 38, however, energizes from the ground potential encounteredLon the busy test contact'by test wiper 51, and again closes a circuitv for rotary 'magnet 53, where upon rotarymagnet 58, energi'zes again and advances the wipers into engagement with the. next set ot bank contacts.

varmature 47, thereby extending ground ahead on test wiper .51 and the selected test contact to the release trunlrceinluctor (S0, making the kseized trunk busy to the other' selectors having raccess to,` it; disconnects ground from armature 40 ofi line re- .lay 35 at `armature 48, thereby openingithe Y au circuit oli' the slow yacting release' relay 36; and at armatures 46 and 49 disconnects the incoming' trunk. conductors Yfrom the windings ot line relay andextends them by way of. wipers 50and-v52 to the corresponding conductors oit the seized trunk. Responsive to the seizureot'` this trunk, holding ground is placed on release trunk conductor (i in the usual manner, resulting in a holdingvcircuit Lt'or relay 39., being-.closed through test wiper 51, and armature 47 and its worling contact before. the slow act-inel rlhe abovey alternate operation of steppingLrelay 38 and release relay 36 has `Returning now to the sender, Fig. 4slow acting pick-up relay 306 deenerglzes atter an interval and opens the locking circuit oit stopy Vrelay 305 at armature 313. Stop relay 305 is also slow acting and maintains its arniature attracted ifor an interval, after which it deenergizes and disconnects stepping magnet 303 from wiper 307 and again connects it with the interrupter 304. It may be pointed out that the interval required for relays 30G and 305 to lall back one after the other is made long enough to permit the change-over and trunk-lnint-ing operations oi the selector D above described to take place before the next diofit is transmitted. Y

The hundreds (S inthe desired number is now transmitted in the same manner as was the thousands digit 5 and is terminmied at the end ot'the sixth interruiiition inthe outgoing control circuit upon the energization of stop relay 305 over the i"ollowing circuit: from ground by way ot the lower armature and working Contact ot relay` :206, lower armature and resting contact of relay 210, righthand armature and resting contact olf relay 2li, right hand armature and resting contactv7 ot relay 212, right hand armature and working Contact of relay Q13, second armature (count-i` ing from the right) ot relay Eiland its working contact, the sixth impulse stop coin ductor 256,'and thence to battery by way ot wiper 308 and stop relay 305. The energization et stop relay 305 results in the wipers of the sender being again advanced to normal position and resultspalso inthe ground potential being removed from conductor 244. whereupon the two-step relay Q10 is energized by its two windings inseries (the lower winding oirelay 210 having energized and ope` ated the. first step lockingcontacts at the beginning of the second digit) and oper-- ates its upper andlower armatures. transiter ring the circuits controlled thereby lo the tens register.

'Responsive lo the transmission ot the second digit G, the selected' hundreds selec-- tor is operated in the same manner` as ile-- scribed for lthe thousands selector l.) und selects an idle connector switch in the usual manner.

The sender is again started and this time sends out the tens digit 7 in the number. which digit is terminated in the usual manner upon the energiza'tion ot stop relay 305 over the following circuit: from ground by way of the lower armature and working con tact of relay G, lower armature and working contact of'lelay 216, lower armature and resting contact of relay 220, right hand armature and working Contact oit relay 221, middle armature and rest-ing contact oi" relay 222, inner right hand armature and resting contact of relay 223, inner right hand armature and resting Contact of relay Q24, the seventh impulse stop conductor 257, the

Ilo

lil() associated contact `in the sender bank, wiper 308, and relay 305 to battery.

Responsive to the transmission of this digit, the selected connector is operated to raise its wipers opposite the seventh level of bank contacts.

The sender is again started and this time sends out the tourth and last digit, the units digit 8, in the desired number. This digit is terminated'by the energization o1 stop relay 305 over the following circuit: from ground by way of the lower armature and working `contact of relay 206, lower armature and working contact ot relay 216, lower armature and working contact et relay 226, right hand armature and. resting contact of relay 231, right hand armature and working contact ot' relay middle right hand armature and` resting contact of relay 233, third armature (counting from the right) and its resting contact oli relay 23d, the eighth impulse stop conductor 258, the corresponding contact in the sender bank,A wiper 303, and stop relay 305 to battery.

`Responsive to the above transmission et the units digit 8, the connector in use op erated to connect with the desired line and thereupon signals the called `subscriber in the usual manner.

Responsive to this energization ol stop relay 305, ground is again removed irom conductor 244. at armature 311,`in addition to the usual closure of the restoring circuits at armatures 309 and 310. Responsive to this removal of ground from conductorlleel, the

two-step relay 236, which also energized part way at the beginning olf thelast digit, energizes through both its windings in series; disconnects ground from the interrupter 304 at its lower armature .so as to prevent the sendertroni again starting ail'ter it is restored; and at its upper armature le moves ground trom conductor 176, opening the circuit ot relay .123 .in the linl; circuit, Fig. 2. Relay 128 accordingly deei'iergizes and replacesthe local bridge across conductors 79 and 80 at the normally closed con* tacts controlled by armature lilf), and at armatures 149 and 150 disconnects the wipers 1111 and 142 from conductors 79 and 80. Relay 123 also opens the locking circuit of start relay (SG o'l2 the inder l? at armature 148, and at armature 147 removes ground from the test conductor ott the link and connects the said test conductor to relay 130 again.` The finder is now rei'ldered lectable to the link selector LS.

Responsive` tothe opening of its locking circuit, relay GGot the finder l? deenergizes and ,opens the circuit oi: relay 21 oit the trunk circuit TC at armature 77, whereupon relay 21 deenergizes and replaces ground on the test conductor 30 at armature 26, and at armatures 23 and 27 disconnects the trunk conductor extending to the selector D from conductors 28 and 29 and connects them to the trunk C11-cuit TC again.

In the finder F, as a further result of the its working contact for stepping magnet 13? A Relay 133, being slow acting, maintains ils armature attracted for an interval and accordingly the circuit oi' stepping magnet 135 remains closed longl enough to energize the magnet. The wipers, however, are not advanced upon the energiaation ot the magnet, the mechanical construction ot' the reg isteihse-nder selector being similar to that et the sender.` liifhen relay 133 deenergizes, it disconnects the wipers lll-l/-G, inclusi ve, at armatures 1631-166, inclusive, thereby treeing the sender. Also relay 133 opens the circuit ot stepping magnet 135 at armature 153, whereupon magnet 135 deenergizes and advances the associated wipers into engagement with the next set oit bank contacts. This step is taken by the wipers in order to insure that the same sender is not repeatedly employed to send out successive numbers. lit this were not done, the registersender selector might become set on a detective sender, thereby completely tying up the service from that link circuit. lilith the )resent arrangements however a new sender` `ergized, the holding ot the connectimi is dependent upon the energization oil? relay 7, which in turn is dependent upon the plugging in of the fr operator. ln ease the A operator has not plugged in, the bridge across the trunk conductors is open at armature 12 ot relay andthe established connection is released. Assuming, however, that the A operator plugged in prior to the deenergization of relay 2l, which she has ample time to do alter the trunk is assigned to her and betere a number set up by the li operator is sent out, relay 7 energzes responsive to the plug et the A operlill) l itl ,l Windingin energizing the` relay.

ators cord circuit being inserted intov they jack J and closes a bridge across the associated trunky conductors at armature 12, Which bridge includes'the impedance 10 and the upper Windin` of the electro-polarized relay 9. Relay 7 also closes a multiple circuit for the lainp 8 and the lowerr Winding of the electro-polarized relay 9.` According#` ly, when the deenergization of relay 2l tr place, the busy lamp 8 remains lighted through armature 13 and its Working' coritact after itsinitial circuitis opened at armature 26 and they connection is held up through the bridge which is closed at ai'nia'g ture 12 of relay 7. The electro-.polarized relay 9, however, is not operated at this time owing to the fact that the current flow in either Winding` opposes the current. flow in the other Winding.

Vhen the called subscrihei" responds to the ringing of his bell, which is-acconiplished by ringing current Vsent out through the` connector switch in the usual manner, the.

`back bridge'rel'ay ofthe connectorstvitch in,

use reverses the direction of c frent iioiv in the calling loop, whereupon the electr@ polarizedrelay` 9 responds owing to the fact. that thecurrent flow in its upper Winding.; noW- assists they current. iioW in its lower Uilen Orff erating, relav 9 places` a shunt around high resistance l1, soi as toA extinguish calling supervisory lainpin the calling,- eratorls cord circuit.

When the called subscriber replaces y receiver, the back bridge, relay in'the con-d nector switchfin use reverses the c uri'ent flow in the calling loop back tornoriii'al, whereupon the electro-pclarized relay 9 .responds by'retracting its armature let, reinsertingthe resistancel 11 in series with relay i' so as to. again lighty the calling;` supervisory laiiip in the A operators cordV circuit. y

When the A operator pullsdown,the

the opconnection at her position, relay t in' thetrunk circuitflC deeiiergizes and opeiisthe circuit of the busy lamp 8 and the lower Winding1 of the electro-polarizedrelay Slat armature l13, and at armature 12 opens the bridge' across the associated conductors leading to the selector D. Responsive tov this, the connectioiiis releasedin theI usual manner, the selector l) being; released responsive to the deenergizationojf switching,` relay 39 Which occurs when ground is r e.` moved from the release trunk conductoijGO. TheK direct release ofthe selector D, itl may lae'pointed out, is .brought about in the usual' inaiinerpby the eneigizatioii ofjrelease magg'-4 net 53 through theresting conta-ct aijinaj tureeS, armature 4Qy and itsresting contact,

armature`l2'and its resting contact, and ofi. normal contacts 54. TheVr circuito` release-V msiet "53 1S ,esem Opened at @itinerant een;

kerate inv the correct manner.

the.

his 4 Accordingly, relay 128 does not energize to,

step the liiik selector LS oli"y the link'circuit :#51 and the'lainplOlV remains lighted, iiiforining the operator that the complete number is not set up. In this case.. thc operator is not sure Whether she failed to depress one or' the keys suiiicieiitly or Whether theregister sety in use failed to op- At anyI rate, theI operator depresses the gize responsive to the energrixgition relay 10G Lincase the sender release button is operated subsequentto the energizationofref lay 128V,l becaiisvethe la, ci; closes a` multiple circuitfor start relay 132 atariiiature 191.

Then theV operater releases-the sender release pi'ish-button, relay 10G deeiiergizes and again,closeathecircuit et relay 132 at :irniuturc 107, whereupon thel register-sender selector RSS is operated to select a| new sender, the one last uscdneu'r heine,- last choice owing tothe (tact that the wipers et theregister-sender sclectorlRSS start on the contacts justahead ol the sender last used. The operator noivtsets upthe desired number in the. usual manner.

lt will no iv be` assumed thatthe B operator has assigned the. trunk circuit TC and that the link circuit #l is in use iii connection withthereeister sender shown iii Figs-v3 and el, butptliatthe4 operator cannot. reineinbertlie correct. nuinber. In this case, the operator, `of course, could setup a predetermined number, that would trunk the call to a monitoring opcrators position,` ln

case, lieu'ever, tliatit isnot desi 'ahle orren-` reeeet to dattie, ,the firearm: may free nder` release, push button, closing a circuit tor relay 10G.`

Relay zile her push buttons by depressing the link release button, thereby placing ground on conductor 110. rlhis closes a circuit 'for the slow to energize relay 103. The tactthat relay 103 slow to energize indicated by a solid black portion ot the core instead et the usual shaded portion, such as the one on the lower end et relay 133. it. relay like .133 is not especially slow to pull up owing to the tact that the copper slug is placed on the heel end thereei', while relay 103 is both slow to pull up and slow to 'tall back, because the copper yslug is placed on the armature end ot the relay, thereby intercepting the lines ot torce on their way tothe armature. The placing oit ground on conductor 110 results in the closing ot a circuit tor stepping magnet 102 in `multiple with relay 103 and `throng-gh armature 101- and its resting contact. `ildagnet 102 accordingly energizes and moves the associated pawl (not shown) into engagement with another notch in the wiper driying ratchet wheel but does not move the switch wipers.

Responsive to the above operations, relay 130, which was formerly energized through stepping magnet 102, deenergizes 'and'opens till the circuit oii start relay G6 at armature 151, and the circuit of relay 131 at armature 1511, whereupon the link circuit is released in the `hereinbeiiore described manner.

fitter an interval which is suiliciently long to allow the stepping magnet 102 to operate telly, relay 103 energizes and dissignal the A operator who will put the call through a new call.

ln case the operator fails to set up a complete number, or in case the register tails to attuate properly to register ti/complete num ber, relay 123 'fails to operate, as `above pointed out; relays 130 and '131 remain energized; and the lamp 101 is not eXtinguished, informing the operator, as pointed out liereinbetorc, that complete number has not been registered, However, owing to a rush oi work, the operator may tail to nete that the lamp 101 is not extinguished after shehas depressed the'last push button, and she may assign a new trunk with the lamp stilllighted. ln thiscase, the link selector stillstanding on the link circuit used in the prmfiously attempted calli and `an idle link circuit is not available for the new call.. Accordingly, arrangements have been provided lor causing the link selector to pre-select a new link circuit in case the start wire is again grounded under the conditions just pointed out. ln this case, when the start wire is grounded, relay 93, F ig. 1, cnergizes over the start wire and places ground on conductor 33, and, since relay 131 is still energized, the ground potential is extended through armature 155 `and its working contact to relay 103 by way of conductor 110, and through armature 104- and its resting contact'to stepping magnet 102. This results in the stepping magnet of the link selector LS being operated in the previously described manner to select a new link circuit, the link circuit in use being released responsive to the deenergization of relay 130. tlince the operator isxinstructed to hold the assign button depressed until she sees her lamp 101 become lighted, the slightly delayed operations, due to the fact that the old link circuit must be treed and a new one pre-selected, do not cause any harm to result, and the operator releases the assign button when she sees the lamp 101 become lighted when the newly allotted link circuit completes its operations.

Regarding the operation ot the twin finder, one ot which may be associated with each of the linders such as l?, it may be stated that this twin finder operates in the same manner as the other finder, its ein cuits being identical with the circuits or the linder 1P. Vlhe one difference is that when a trunk is assigned in the group to which the twin iinder has access, the start wire of the twin finder instead oli thestart wire of the liuder li is grounded, whereupon the start relay oit the twiniinder instead oit' the start relay oi the `tinder lF is operated. Relay 98 of course common to both finders, one winding associated with each.

Referring now particularly to Figs. `and 0, the desirable inodiiication shown therein will new be explained. rlthe principal dit terence between the arrangement shown in Figs. 5 and G and the arrangement shown in F 1 and 2 is that the mechanical finders, such as l?, have beenreplaced in Fig. 5 with a relay per trunk 'for each of the link circuits, and the remaining circuits have been suitably moditied, the circuits of the register sender and; oi the register-sender selector, however, being the same in both cases.

lt is thought that the modilication will be best understood from a detailed description et its operation. it will be assumed that the E operator at whose position the equipn'ient shown in ."lli 5 and' is located, receives ay call over the order wire and assigns the idle trunk cinruyrising conductors 401] and 102 to the lior this purpose,

llO

lll'i lili! i431, 432, and 433.

calling A operator. The. B ,operator thereupon `operates the assign key 413, placing ground on conductors 414, 415, land 416 leading to the lower windings ot relays Y y Relay 431 is individual to the linky circuit #1 and relays 432 and 433 are indivi-dual to the linlcircuits .qt/:2'

`and #3", respectively. Since the link setacts oi theassien ke conductor 414 lower winding otl relay 431, conductor 454, resting contact vand armature 534, resting Contact and spring 511 of the busy key, the test wiper V526 of the switch LS', interrupter contacts 505 `and stepping magnet 502 to i battery. Stepping magnet 502 does not energize over this circuit on account ot the high resistance 'ot the lower winding of relay 431. Relay 431, upon energizing, loclrs itself to ground at armature 438 independent ofconductor 414; connects the closed bridge including conductors 452 and 453 across the conductors 444 and 445 leading totheassociated selector switch and disconnects the said conductors from the open bridge in the trunk circuits TC at armatures 434 and 439; closes a circuit for the lower winding of the electro-polarized relay 404 and the busy lamp 408 at armature 435.; prepares a locking circuit for its upper winding `at armature 437; and at armature 436 closes a starting circuit for the registersender yselector RSS as follows: from ground by way of the resting contact and left hand armature ot' relay 440, working contact and armature 436; conductor 456, start relay 528, and the resistance 530 to battery. Relay 528, however, does not energize as long as the assign key is depressed, owing to the ground potential vapplied over the common, conductor 457 and through armature 537 and its restingy contact to the junction ot the winding of relay 528 and the resistance 530.` Y

Y When the operator releases the assign key, the lower winding of relay 431 remains .locked up at armature 438, and ground is removed from conductor 457, permitting Y start relay 528, Fig. 6, to energize over its circuit tracedl above. Upon energizing, relay 528 disconnects conductor 457 from the junction otits own winding and the resistance 53.0 ,at armature. 537 and extends the said conductor through armature 537 and yits workingcontact, and through the resting Contact and armature 531 tothe common linlr release conductor 510 so as to cause a new linlr to be allotted in case the '1 ,cenare operator depresses another assign key before the call over the trunk circuit TC has been set up. Relay 523 also closes a circuit tor relay 529 and stepping magnet 548 in series at armature 538, and at armature 539 connects test wiper 555 to the junction ot relay 520 and magnet 543. Accordingly, the register-sender selector RSS selects an idle register sender in the hereinbe'lore described manner, whereupon relay 529 energizes and seizes the selected register sender, and at armature 547 closes a circuit for the lamp 501 to iniiorm the operator that she may set up the number.

The operator now sets up the desired number in the usual manner, and, when the number is completely set up, conductor 175 is grounded by the register in the usual inanner, closing` a circuit through wiper 556 and armature 546 and its working contact for relay 527, whereupon relay 527 encrgizes; closes a local circuit for start relay 523 at armature 533; closes a lockingl circuit tor the upper winding of relay i531 at armature over conductor 455 and through armature 437 and its working contact; disconnects the common conductor 510 trom conductor 457 at armature 53l; at armature 534 opens the circuit ol` the lower winding oit relay 431, leaving the said relay 431 energized over its upper winding; and at armature 534 and its working contact places ground on the test conductor leading to the bank of the link selector LS. Accordingly, the link selector LS is .stepped oli"i the link :tt-1 by the action olf `cpping magnet 502 and pre-selects another idle link circuit.

Then the registered number has been completely sent out, ground is removed l'rom conductor 176 by the register in the hereinbetore described. manner, whereupon relay deenergizes; opens the circuit of relay 528 at armature 533 and the locking circuit of relay 431 at armature 532. lllhen this.1

occurs, the relay 43.1 deenergizcs and reconnects the two sections ol the trunk extending ahead lrom the trunk circuit TC.

ln the register-sender selector, relay 52h' deenergizes responsive to the opening of its circuit and opens the circuit olil the slow acting relay 520 at armature 538 and closes a circuit tor stepping magnet through armature 540 and its working contact. Accordingly, stepping magnet 548 is energized, and, responsive to the (leenergization et relay 529, stepping magnet 543 drenergizes and advances the associated wipers one step.

Regarding the holding up oit the estalilished' connection, it may he pointed out that the connection is held up in the saine manner as was described in connection with Fig. l` that is, after the A operator has plugged in` relay 403 is energized and a circuit is closed at armature 400 lor relay 405, which llt) relay maintains the circuit of the lower winding of relay 404 and of the busy lamp 408 intact at armature 412 after relay 431 has deenergized, and likewise holds the established connection at armature 411 through the bridge including the impedance 407 and the upper winding ot the electropolarized relay 404.` y

Vhen the called subscriber responds, the electro-polarized relay 404 is operated and it shunts the high resistance winding ot re* lay 403 with the low resistance impedance 406 at armature 410, thereby permitting the calling supervisory lamp in the A opera tors cord circuit to be extinguished. The impedance 406 is included in the shunt around the high resistance winding of relay 403 in order `to make the talking circuit more eliicient than it would otherwise be with the lower winding only of relay Y403 back and removes the shunt from around v thehigh resistance windingoii relay 403, whereupon the calling supervisory lamp is again lighted and the operator pulls down the connection, resulting in the deenergization of `relay 403 followed by the dcenergization of relay 405. The busy lamp 403 now'becomes extinguished and the connection is released in the usual manner respon sive to the opening of the bridge at armature 411.

In case the operator has partially set up a number' and wishes to wipe out that number, she presses the sender release button in the upper lett hand" corner of Fig. 6, closing a circuit over conductor 451 tor relay 440, whereupon relay 440 energizes and removes ground from conductor 441, opening the circuit ot start relay 523, Fig. 6, whereupon startrelay 52S deenergiaes tollowed by the deenergization of the slow acting relay 529. momentarily energized in the usual manner and the associated wipers are advanced into engagement with the nest set ot bank contacts.

`When the operator releases the sender release button, the circuit of relay `523 again established and a new sender is ylected in the usual manner, whereupon the operator may set up any desired number.

In case the operator desires to release the link, if she nds that she is unable to set up a certain number', or to remember the number, or for any other reason, sheoperates the link release button, causing a momentary impulse of current to be delivered to stepping magnet 502 owing` to the slow to pull up action of relay 503. Accordingly, the circuit of the lower winding of relay 431, Fig. 5, is opened and the relay deenergizes and opens the circuit of start relay at armature 430,

The stepping magnet 548 is whereupon the register-sender selector RSS is released in the usual manner.

The link circuit is released in the same manner and a new one is pre-selected in case the operator presses a new assign key before the previous number is completely set up or, in other words, before relay 527 has been energized over conductor 17 0. In this latter case start relay 528 of the link circuit (assuming that this link circuit is the one in use for the previous call) is energized and relay 527 is deenergized. Accordingly, when the common conductor 457 is grounded upon the new assign key being operated, a ground potential is extended to conductor 510 through armature 537 and its working contact and the resting contact and armature 531. After the link selector LS has operated to pre-select a new link circuit, con nection is made with the assigned trunk and with an idle register-sender selector in the hereinbefore described manner.

That l claim is:

1. In a telephone system, a plurality of trunk lines, a plurality of sending mechanisins, a set oit number keys, a signal individual to said keys, operator controlled automatic means for connecting said key set with an idle sender and for connecting said sender with a calling trunk line, and means responsive only to the completion of both operations tor operating said signal.

2. In a telephone system, a link circuit comprising a forward hunting switch and a plurality ot backward hunting switches, a plurality of starting circuits, one for each oi? said backward hunting switches,means for closing any one `of said starting circuits, and means responsive thereto tor' starting the corresponding backward hunting switch and for directly starting said i'orward limiting switch.

3. ln a telephone system, a plurality oit trunk lines, a plurality of sen ders, a plurality of link circuits for connecting any sender to any trunk line, a link allotter, means incl uding testing means :tor automatically maintaining said allotter associated with au idle link circuit, and operator controlled means for advancing said. allot-ter independent of said automatic means. y

4. In a telephone system, a plurality ol" register senders,'a plurality of trunk lines, a plurality oit link circuits, each having mechanism tor connecting any desired line with any idle register sender, a link allotter l'or allotting only one link circuit lor use at one time, an assign key tor each line, means responsive to the operation ot an assign key for causing' the allotted link circuit to connect the line associatedwith the operated assign key with an idle register sender, means for operating the selected registering mechanism through the link circuit in use to register a desired number-,means for subs` flu quently transmitting the registered number .idle sender.

o 5 In a telephone system, a plurality of :trunk lines extending to automatic s "'itches, a plurality ot register senders, a group or link circuits for connecting idle senders with trunk lines over which calls are to be ei;- tended,` an operators key set, preselecting switchingmeans for maintaining said set ,connected with an idle link circuit and for preventing connection ywith busy link circuits, means responsive when the operator assigns one of said trunks to a call tor causing the preselected link circuit to connect an idle register sender to the assigned trunk, circuit arrangements for causing number set up on said key set to be registered in the connected register sender, and means responsive to theregistration ot' the last d' in the number for causing the connected re ter sender to transmit the number thi-ouf the link circuit in use to the connected trunk line. i i I i' i V(plin a telephone system, a plurality of trunk linesextending to automatic switches, aYplu-rality of register senders, a group ot link circuits for connecting idle senders with indy ltrunk linesv over which callshare tobe ei;-

tended, an operators key set, preselecting switching means 'for maintaining` said key set connected with anl idle link circuit and for preventing connection with busy link circuits, means responsive when the operator assigns one of said trunks to a call for causing the preselected link circuit to connect an idle register sender to the assigned trunk,

` circuit arrangements for causing a number 'Y ce set up on saidA key setto be registered in the connected register sender, and means responsive to the registration of the last digit in thenumber for causing the said switching meansxto preselect another one ot said link circuits.

7.111 a. telephone system, a plurality of trunk linesextending to automatic switches, a. plurality otregister senders` a group ol linkcircuits for connecting idle senders with trunk lines over which Vcalls `are to be extended, Van operators key set, preselecting switching means Afor, maintaining said key set connected with an idle link circuit and vfor preventing connection with busyA link idle register V.sender to the assigned trunk,

metteva circuit arrangements for causing a number set up on said key set to be registered in the connected register sender, and means responsive to the registration of the last digit in the number for causing the connected regis ter sender to transmit the number through the link circuit in use to the connected trunk line and for causing the said switching means to preselect another one ot .said link circuits.

S. ln a telephone. systemv` a plurality of trunk lines extending to automatic switches, .other switches, a plurality oit register senders, a group of link circuits for connecting idle senders with trunk lines over which calls are to be extended, :in operators key set, preselecting switching means tor maintaining said key set connected with an idle link circuit, means responsive when the operator assigns one of said trunks to a call for causing the preselected link circuit to connect an idle register sender to the assigned trunk, circuit arrangements for causing a number set up on said key set to be registered in the connected regis er souder, means responsive to the registration of the last digit in the number tor causing the connected register sender to transmit the number through the link circuit in use to the connected trunk line to operate the associated switch and a plurality of said other switches to complete the connection to the called line, means for c0nnecting the calling line to the trunk line prior to the completion of the operation of said switches, means responsive to the transmission of the last digit in the number for disconnecting the connected register sender from the trunk, and means for automatically releasing all the operated switches in case the calling line has not yet been connected to the trunk line when the register sender is disconnected.

9. In a telephone system, a plurality of' trunk lines extending to automatic switches` a plurality of register senders, a group of link circuits for connecting idle senders with trunk lines over which calls are to be extended, an operator-s key set, preselecting switching means for maintaining said key set connected with an idle link circuit`r means responsive when the operator assigns one of' said trunks to a call for causing the preselected link circuit to connect an idle register sender to the assigned trunk. circuit arrangements for causing a number set up ou said key set to be registered in the connected register sender, means for causing the register sender to transmit the registered number through the link circuit in ,use to the counected trunk line, means ,tor connecting a calling line to the trunk line, and circuit arrangements for starting the transmission of the number responsive to the registration of 'the last digit indei'iendent of whether Atbe calling line h as been connected or not;

lili

near-sara lector to select and connect up another reg-` ister sender While maintaining the said trunk linder operated.

l1. In a 'telephone system,` an operators link circuit, aplurality of regl f senden-i, a step-by-step hunting switch lor connecting said link circuitto an idle register sender,

operator-controlled means lor disconnecting said link `circuit from a selected register sender and for advancing said hunting switch one step, and means for thereupon automatically operating said hunting sivitcl to connect said link circuit with another idle register sender. l

l2. In a telephone system, an operatori-i link circuit, a plurality o register senders, a hunting switchfior connecting said li. 1. circuit With an idle register sender, means for releasing said limiting switch to sever said connection, and means automatically operated upon sush release ior advancing said hunting switch a single step to associate it With another register sender.

13. In a telephone system, a plurality ot trunk lines, a plurality oit register senders, a plurality of link circuits, eacii having mechanism i'or connecting any desired line with an idle one oit said register senders, a link allotter for allotting said link circuits for use one at a time, an assign key tor each trunk line, means responsive to the operation of an assign key for causing the allotted link circuit to connect the associated line With an idle register sender, and means responsive to a reoperation oit the last named assign key for causing said allotter to allot another link circuit for use.

14. In a telephone system, a plurality of trunk lines, a plurality oit register senders,

a plurality of link circuits, each having mechanism for connecting any desired line With an idle one oiE said register senders, a link allotter for allotting said link circuits for use one at a time, an assign key vlor each trunk line, means responsive to the operation of an assign key tor causing the allotted link circuit to connect the associated line With an idle register sender, and means responsive to an operation oi any assign key for advancing said allotter to another link circuit whereby a first link circuit is released and the neWly-allotted link circuit is operated to connect the trunk line associated with the last-operated assign key to an idle register sender.

l5. lin atelephone system, a plurality olf" trunk lines, a plurality of register senders, a plurality ot link circuits, each having mechanism 'lor connecting any desired line with an idle one of said register senders, a link all/otter ior allotting said link circuits 'lor use one at a time, 'an assign key 'For each trunk line, means i sponsive to the op-` eration oit an assign key lor causing the allotted link circuit, to connect the associated line 'with an idle register sender, opei,'ator-coiitrolled means 'for registering au 'telephone ninnlirr on the selected register sender, means respoirive to a reoperation oit' the lastnamed u keyprior to the register ing operation lor causing said allotter 'to allot another link circuit ior use, and means controlled from the register sender respon sive to the registering operation for remov- "letter from under the control oil assign key. l

V1G. lin a telephone system, a plurality ot trunk lines, a plurality oi' register senders, a plurality ot link circuits, each haviug mechanism :tor connecting' any" desired lineivith an idle one of4 said register senders, a link allotter l'oif allotting said linkcircuits ior use one at a time, an assign key for each trunk line, means responsive to the operation et an assign key ior causing the allotted link circuit to connect the associated. line with an idle register sender, means responsive to the reoperation of the lastoperatcd assign key tor causing said allotter to allot another link circuit tor use, and operator-cimtrolled means for removing said allotter i'rom under the control of said assign key.

17. lin a telephone system, a plurality oil trunk lines, a plurality of register senders, a plurality oi link circuits, each having mechanism :lor connecting any desired line with an idle one of said register senders, a

'link allotter i'or allotting said link circuits ior use one at a time, an assign key for each trunk line, means responsive to the operation ot an assign key tor causing the allotted link circuit to connect the associated line With an idle register sender, and means responsive to the operation ot said assign key tor rendering said allotter responsive to a subsequent operation of the same or another assign key to allot a new link circuit and release the iirst one.l

lll. ln a telephone system, a plurality ot trunk lines, a plurality of register senders, a plurality oi link circuits, each having mechanism for connecting any desired line with an idle one of said register senders, a link allotter iler allotting said link circuits for use one at a time, an assign key for each trunk line, means responsive to the operation ot an assign key ltor causing the allotted link circuit to connect the associated line with an idle register sender, operator-controlled Elli lll)

means for operatingthe seized register sender to register and retransmit a number, means controlled by the register sender foireleasing the link circuit when the number has been retransmitted, and operator-controlled means for bringing about the release of vthe link circuit independent oi the operation of the register sender.

19. In a telephone system, a plurality of operators flink circuits, a link allotter fer allotting said circuits for use one at a time, a test Wiper anda driving' magnet for said allotter, means for operating said driving magnet in a circuit through said test Wiper tobring about said allotting action, and operator-controlled means for operating said magnet to advance said allotter in a circuit v independent of said test wiper.

aboutsaid allotter action, means in eaeh link cireuit for closing said test-Wiper eireuit to move the allotter to the next link circuit,

igeeaara and a circuit independent of the said test Wiper for operating said magnet.

21. In a telephone system, a plurality of trunk lines, a plurality of register senders, a plurality of link circuits each having mechanism for connecting any desired line with an idle one of said register senders, a. link allotter for allotting said link circuits for use one at a time, an assign key for each trunk line, an allotter-adyance key individual to said allotter, means responsive to the operation of an assign key for causing the allotted link circuit to connect the associated line with an idle register sender, means responsive to an operation of the same or an other assign key for causing said allotter to allot another link circuit for use, means in each of said link circuits for causing said allotter to allot another link lcircuit for use, and means including' said allotter-advance key for causing said :illotter to allot another link circuit.

Y In Witness whereof, I hereunto subscribe my name this 15th day of January, A. D., 1924.

MARTIN L. NELSON. 

